Mechanical and chemical-mechanical polishing processes (collectively, “CMP”) remove material from the surfaces of semiconductor workpieces in the production of microelectronic devices and other products. For example, many conventional semiconductor workpieces include polysilicon as a component for forming conductive and/or semi-conductive microelectronic structures (e.g., plugs or damascene lines). These polysilicon structures are typically formed by depositing a blanket polysilicon layer on a workpiece and removing the excess polysilicon material external to the plugs or damascene lines using a CMP process.
One problem associated with polishing polysilicon is that it is difficult to efficiently clean the workpiece surface after polishing. It appears that particles (e.g., abrasive elements from a polishing liquid and/or a polishing pad, particles removed from the workpiece, or other contaminants) can be adsorbed to the workpiece surface after the polysilicon material has been removed. Such adsorption can be strong enough to render conventional physical treatments (e.g., de-ionized water rinsing, megasonification, and brush cleaning) ineffective for removing at least some of the adsorbed contaminants from the workpiece surface after polishing.
One approach to addressing this problem is to treat the workpiece surface with a chemical solution after polishing. The chemical solution typically includes organic surfactants, hydrogen fluoride, ammonia hydroxide, and/or other suitable chemical compounds. A drawback with this approach is that the additional chemical treatment adds to the cost of the overall manufacturing process and reduces the product throughput. A further drawback is that the chemical treatment may use compounds (e.g., organic surfactants) that are not environmentally friendly, and may therefore be costly to dispose of. Accordingly, there is a need for an efficient and cost-effective technique for removing polysilicon materials from semiconductor workpieces.